Eye examination chart projector

Abstract

The present invention discloses a chart projector for vision test, the chart projector for vision test comprising: one or more image display devices, which generate chart images for vision test; a beam splitter, which, when generating the chart image in the line of sight direction of the eye to be tested, allows a part of the chart image to pass through to illuminate the eye to be tested, and reflects the remaining part to block the illumination of the eye to be tested (5), and when generating the chart image on the side of the line of sight direction of the eye to be tested, allows a part of the chart image to be reflected to illuminate the eye to be tested, and allows the remaining part to pass through to block the illumination of the eye to be tested; and a light sensor, which measures the brightness of the chart image reflected by the beam splitter to calculate the brightness of the chart image for vision test emitted to the eye to be tested through the beam splitter, or measures the brightness of the chart image passed through the beam splitter to calculate the brightness of the chart image for vision test reflected by the beam splitter and emitted to the eye to be tested.

Description

Technical Field

[0001] The present invention relates to a vision test chart projector, and more particularly, to a vision test chart projector capable of detecting the brightness of a vision test chart irradiated to a subject's eye. Background Art

[0002] Binocular vision is the term corresponding to monocular vision, which refers to the method of recognizing objects recognized by both eyeballs as one object through the assistance of both eyeballs when looking at an object with both eyes. Even if you look at the same object, the positions of the left eye and the right eye will differ by about 6 cm, so the images reflected in the left eye and the right eye will be slightly different, which is called binocular parallax. Despite such parallax, the objects we usually see are fused into one image rather than overlapping images, which is called binocular fusion. That is, when objects of similar shapes are displayed to the right eye and the left eye respectively, the human brain will fuse the images recognized by the two eyes and recognize that there is one object. On the contrary, when objects of completely different shapes are displayed to both eyes, the images recognized by the two eyes are recognized separately and will not be fused into one. This is called visual field competition.

[0003] In order to test such binocular vision function, an eye chart projector for projecting an eye test chart onto the right eye and the left eye of a subject is known. Figure 1 This is a diagram for explaining the working principle of a polarized chart projector used in a conventional binocular vision test. Figure 1 As shown in FIG. 1 , a conventional polarization table projector includes an image display device 10 such as an LCD that displays a visual acuity chart of a predetermined shape, and a sheet-like polarizing film 20 attached to the front surface of the image display device 10. In the polarizing film 20, polarizations are alternately arranged in one direction ( Figure 1 Line-shaped polarization zones 20a and 20b extending in the horizontal direction (in the horizontal direction). The polarization zones 20a and 20b include a first polarization zone 20a and a second polarization zone 20b in a manner that generates a pair of table images with mutually orthogonal polarization axes when light of the table image emitted from the image display device 10 passes through. The first polarization zone 20a is an optical zone for the right eye, and its optical main axis direction is configured to convert the table image into a polarization having a polarization axis direction that is consistent with the polarization axis direction (135 degree direction) of the polarization filter 22a for the right eye. On the other hand, the second polarization zone 20b is an optical zone for the left eye, and its optical main axis direction is configured to convert the table image into a polarization having a polarization axis direction that is consistent with the polarization axis direction (45 degree direction) of the polarization filter 22b for the left eye.

[0004] In such a polarization table projector, when the image display device (10) is operated in a manner to display the desired table shape in the first polarization zone 20a and the second polarization zone 20b, and the right eye polarization filter 22a and the left eye polarization filter 22b are worn on the right eye and the left eye of the subject, the right eye and the left eye of the subject only observe the table images of the first polarization zone 20a and the second polarization zone 20b, respectively, so that a binocular vision test can be performed by checking how the subject recognizes them.

[0005] The inventor's Korean patent application No. 10-2020-0104771 (filing date: August 20, 2020) discloses a table projector that implements such a polarization table in a completely new way. The polarization table projector disclosed in the above application generates a polarization table by integrating two tables that are respectively irradiated (projected, radiated) by two image display devices into a beam splitter (e.g., a half mirror). However, since the table projector emits tables from two image display devices respectively, the brightness of the table images emitted by the two image display devices may be different from each other, and the brightness of the table image is reduced when passing through or reflected by the half mirror, so there is a concern that the table image may not have the predetermined brightness required for vision testing. In addition, as the image display device ages, the brightness of the table image may also drop below the predetermined value required for vision testing.

[0006] Prior art literature

[0007] Patent Publication No. 10-2011-0035876 (publication date: April 6, 2011). Summary of the invention

[0008] Technical issues

[0009] Therefore, an object of the present invention is to provide a table projector for vision testing that can detect the brightness of a table image that has passed through a beam splitter such as a half mirror.

[0010] Another object of the present invention is to provide a table projector for vision testing that can adjust the brightness of table images emitted by two image display devices to be the same.

[0011] Technical Solution

[0012] In order to achieve the above-mentioned object, the present invention provides a chart projector for vision examination, comprising: one or more image display devices 30a, 30b, which generate chart images 40a, 40b for vision examination; a beam splitter 50, which, when generating the chart image 40a in the direction of sight of the eye 5 to be examined, allows a part of the chart image 40a to pass through so as to be irradiated to the eye 5 to be examined, and reflects the remaining part to block the irradiation to the eye 5 to be examined, and when generating the chart image 40b on the side of the direction of sight of the eye 5 to be examined, allows the chart image 40a to pass through so as to be irradiated to the eye 5 to be examined, and reflects the remaining part to block the irradiation ... A portion of the table image 40b is reflected by the beam splitter 50 to irradiate the eye to be examined 5, and the remaining portion is allowed to pass through to block the irradiation to the eye to be examined 5; and a light sensor 60, which measures the brightness of the table image 40a reflected by the beam splitter 50 to calculate the brightness of the table image 40a for vision examination emitted to the eye to be examined through the beam splitter 50, or measures the brightness of the table image 40b passed through the beam splitter 50 to calculate the brightness of the table image 40b for vision examination reflected by the beam splitter 50 and emitted to the eye to be examined 5.

[0013] In addition, the present invention also provides a chart projector for vision testing, comprising: a first image display device 30a, which projects a first chart image 40a polarized in a first direction; a second image display device 30b, which projects a second chart image 40b polarized in a second direction; a beam splitter 50, which allows the first chart image 40a emitted by the first image display device 30a to pass directly, and projects the first chart image 40a polarized in the first direction toward the subject's eye, and reflects the second chart image 40b polarized in the second direction emitted by the second image display device 30b, and projects the second chart image 40b polarized in a third direction different from the first direction toward the subject's eye; and a light sensor 60, which measures the brightness of the first chart image 40a emitted by the first image display device 30a and reflected by the beam splitter 50 to calculate the brightness of the first chart image 40a projected to the subject's eye 5, and measures the brightness of the second chart image 40b emitted by the second image display device 30b and passed through the beam splitter 50 to calculate the brightness of the second chart image 40b projected to the subject's eye 5.

[0014] Effects of the Invention

[0015] The eye test chart projector of the present invention can detect the brightness of the chart image that has passed through a beam splitter such as a half mirror, and can adjust the brightness of the chart images emitted by two image display devices to be the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram for explaining the operating principle of a conventional polarization table projector for binocular vision testing.

[0017] Figure 2 and Figure 3 It is a perspective view and a cross-sectional view in the direction of the light path showing the structure of a vision test chart projector according to an embodiment of the present invention.

[0018] Figure 4 It is a diagram showing the structure of a vision test chart projector according to another embodiment of the present invention.

[0019] Figure 5 is to show that the subject recognizes Figure 4 The diagram shown is a diagram of the state of the polarization table emitted by the polarization table projector. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below with reference to the accompanying drawings. In the accompanying drawings, elements that perform the same or similar functions as in the past are given the same reference numerals.

[0021] Figure 2 and Figure 3 1 is a perspective view showing the structure of a vision test chart projector according to an embodiment of the present invention and a cross-sectional view in the direction of the light path. Figure 2 and Figure 3 As shown, the eye test chart projector of the present invention includes one or more image display devices 30a and 30b, a beam splitter 50, and a photo sensor 60 (photo sensor).

[0022] The image display devices 30a and 30b generate chart images 40a and 40b for vision testing. The image display devices 30a and 30b may be any image display devices capable of generating chart images 40a and 40b, for example, liquid crystal display devices (LCDs), organic light emitting devices (OLEDs), etc. The generated chart images 40a and 40b are irradiated to the subject's eye 5 through the beam splitter 50 or reflected by the beam splitter 50 according to the generation position of the chart images 40a and 40b. Specifically, the beam splitter 50 may allow a portion of the chart image 40a to pass through to irradiate the subject's eye 5 when the chart image 40a is generated in the line of sight direction of the subject's eye 5, and reflect the remaining portion to block the irradiation to the subject's eye 5, and when the chart image 40b is generated on the side of the line of sight direction of the subject's eye 5 (for example, in a vertical position), a portion of the chart image 40b is reflected to irradiate the subject's eye 5, and the remaining portion is passed through to block the irradiation to the subject's eye 5. For example, the first image display device 30a located in the line of sight direction of the subject's eye 5 generates an image 40a for a vision test chart that is emitted to the subject's eye 5 through the beam splitter 50, while the second image display device 30b located on the side of the line of sight direction of the subject's eye 5 generates an image 40b for a vision test chart that is reflected by the beam splitter 50 and emitted to the subject's eye 5.

[0023] The beam splitter 50 is a common device that reflects a portion of the incident light and allows another portion to pass through. For example, it can be a pair of prisms joined in a hexahedral shape, a half mirror, a dichroic mirror prism, etc., preferably, a half mirror. The brightness of the table image reflected by the beam splitter 50 and the brightness of the table image passing through the beam splitter 50 can be different depending on the light passing through the beam splitter 50 and the reflection ratio. However, when the brightness of the table image incident on the beam splitter 50 is 100, it is preferred that the brightness of the table image reflected by the beam splitter 50 and the brightness of the table image passing through the beam splitter 50 are the same as each other, that is, 50 (50% of the incident light is transmitted and 50% is reflected). Thus, when the table images generated by the image display devices 30a and 30b are separated by passing through the beam splitter 50 or reflected by the beam splitter 50, the brightness of the table images irradiated to the subject's eye 5 is reduced, and thus a table having a brightness value required by the table projector, for example, 80 to 320 cd / m 2 In this case, it is necessary to increase the brightness of the chart image itself generated by the image display devices 30a and 30b. Therefore, in the eye test chart projector of the present invention, the brightness of the eye test chart images 40a and 40b emitted by the image display devices 30a and 30b can be adjusted according to the brightness of the eye test chart images 40a and 40b detected by the optical sensor 60.

[0024] The optical sensor 60 measures the brightness of the table image reflected by the beam splitter 50 to calculate the brightness of the table image for vision examination emitted to the eye under test 5 through the beam splitter 50, or measures the brightness of the table image passed through the beam splitter 50 to calculate the brightness of the table image for vision examination reflected by the beam splitter 50 and emitted to the eye under test 5.

[0025] As described above, since the brightness of the table image generated by the image display devices 30a and 30b is divided at a predetermined ratio by the beam splitter 50, when the brightness of the table image reflected by (or passing through) the beam splitter 50 is measured, the brightness of the table image passing through (or reflected by) the beam splitter 50 can be calculated. Specifically, when the first image display device 30a located in the direction of the line of sight of the eye to be tested 5 generates a table image for visual acuity testing, and the generated table image is separated by the beam splitter 50, the brightness of the table image reflected by the beam splitter 50 is detected, and the brightness of the table image emitted to the eye to be tested 5 through the beam splitter 50 can be calculated. Similarly, when the second image display device 30b located on the side of the line of sight of the eye to be tested 5 generates a table image for visual acuity testing, and the generated table image is separated by the beam splitter 50, the brightness of the table image passing through the beam splitter 50 is detected, and the brightness of the table image reflected by the beam splitter 50 and emitted to the eye to be tested 5 can be calculated. According to the present invention, since the brightness of the table image that does not travel to the subject's eye 5 through the beam splitter 50 is indirectly measured, the optical sensor 60 can be located at a position away from the travel path of the table image emitted to the subject's eye 5. In this way, after measuring the brightness of the table image emitted to the subject's eye 5, when the brightness of the table image deviates from the desired predetermined brightness, it is possible to provide a method for adjusting the brightness of the image display devices 30a, 30b, that is, the brightness of the table image generated by the image display devices 30a, 30b is manually or automatically adjusted so that the brightness of the table image emitted to the subject's eye 5 becomes the desired predetermined brightness.

[0026] Figure 4 FIG. 2 is a diagram showing the structure of a table projector for vision testing according to another embodiment of the present invention, which shows a state where the table projector for vision testing according to the present invention is applied to a polarization table projector for binocular vision testing. Figure 4 As shown, the first image display device 30a projects a first image 40a polarized in a first direction, and the second image display device 30b projects a second image 40b polarized in a second direction. The beam splitter 50 allows a portion of the first image 40a emitted by the first image display device 30a to pass through, so as to project the first image 40a polarized in the first direction toward the subject's eye 5, and reflects a portion of the second image 40b polarized in the second direction emitted by the second image display device 30b, so as to project a second image polarized in a third direction different from the first direction toward the subject, that is, the subject's eye 5.

[0027] In order to perform binocular vision test, the first image 40a emitted by the first image display device 30a and projected in the direction of the subject's eye 5 should be recognized by only one of the two eyes of the subject's eye 5, and the second image 40b emitted by the second image display device 30b and projected in the direction of the subject's eye 5 should be recognized by only the other of the two eyes of the subject's eye 5, so the first polarization direction of the first image 40a and the third polarization direction of the second image 40b should be different from each other. For example, Figure 4 As shown, when the first polarization direction of the first table image 40a emitted by the first image display device 30a is 45 degrees, since the polarization direction of the first table image 40a passing through the beam splitter 50 is also 45 degrees, the subject recognizes the first table image 40a polarized at 45 degrees. On the other hand, when the second polarization direction of the second table image 40b emitted by the second image display device 30b is 45 degrees, since the polarization direction (third direction) of the second table image 40a reflected by the beam splitter 50 is 135 degrees, the subject recognizes the second table image 40b polarized at 135 degrees. When polarized light is reflected from a mirror, the polarization angle changes. For example, when light polarized at 45 degrees is reflected from a mirror at a reflection angle of 90 degrees, light polarized at 135 degrees is reflected. In the present invention, such characteristics are utilized to generate table images 40a and 40b with different polarization directions.

[0028] At this time, the optical sensor 60 measures the brightness of the first image 40a emitted by the first image display device 30a and reflected by the beam splitter 50 to calculate the brightness of the first image 40a projected to the eye under test 5, and measures the brightness of the second image 40b emitted by the second image display device 30b and passed through the beam splitter 50 to calculate the brightness of the second image 40b projected to the eye under test 5. For accurate brightness measurement, when measuring the brightness of the first image 40a emitted by the first image display device 30a, the second image display device 30b is in a closed state, and when measuring the brightness of the second image 40b emitted by the second image display device 30b, the first image display device 30a is in a closed state. Figure 4 As shown, when the first image display device 30a and the second image display device 30b are used to generate the table images 40a and 40b having different polarization directions, due to the difference in the mechanisms of the first image display device 30a and the second image display device 30b, not only the brightness of the first table image 40a and the second table image 40b is different from each other, but also the intensity of the light is weakened when passing through the beam splitter 50 such as a half mirror or reflected by it, so that the first table image 40a and the second table image 40b emitted to the subject's eye 5 cannot have the brightness value required by the table projector, for example, 80 to 320 cd / m 2Thus, when a brightness difference occurs between the first table image 40a and the second table image 40b, for example, when the brightness of the first table image 40a is 80 cd / m 2 The brightness of the second table image 40b is 320cd / m 2 When the polarization image is used, the visual inspection using the polarization image will be inaccurate, so the brightness of the first table image 40a and the second table image 40b is adjusted to be above a predetermined reference value (for example, 200 cd / m 2 , ISO standard: ISO-8596, third edition, 2017-11, p5, 4.6 Luminance). Therefore, according to the present embodiment, the brightness of the first table image 40a and the second table image 40b emitted to the subject's eye 5 can be adjusted to be the same according to the brightness of the table images 40a and 40b for vision testing detected by the optical sensor 60.

[0029] Figure 5 is to show that the subject recognizes Figure 4 The polarization table projector shown in FIG. Figure 5 As shown in (A), Figure 4 The polarization table projector shown projects in a first polarization direction ( Figure 5 The first table image 40a polarized in the direction of 45 degrees) and the third polarization direction ( Figure 5 In this case, when the subject's right eye wears a second polarization direction (135 degrees) polarized image 40b. Figure 5 When the right eye uses the polarization filter 22a with a polarization of 45 degrees ( Figure 5 (B)), the subject's right eye can recognize the first polarization direction ( Figure 5 , 45 degrees) polarized first table image 40a, but to the third polarization direction ( Figure 5 The second table image 40b with a polarization of 135 degrees is blocked and cannot be recognized ( Figure 5 Similarly, when the left eye of the subject wears the third polarization direction ( Figure 5 When the left eye uses polarization filter 22b with polarization of 135 degrees ( Figure 5 (B)), the subject's left eye can recognize the third polarization direction ( Figure 5 , 135 degrees) polarized second table image 40b, but to the first polarization direction ( Figure 5 The first table image 40a polarized at 45 degrees is blocked and cannot be recognized ( Figure 5 (C)). Therefore, it is possible to perform binocular vision inspection of the subject by projecting different tables to the right eye and the left eye of the subject.

[0030] In the polarized vision chart projector of the present invention, as for the difference between the first polarization direction of the first chart image 40a and the third polarization direction of the second chart image 40b, it is sufficient that one of the first chart image 40a and the second chart image 40b is recognizable only by the right eye and the other is recognizable only by the left eye by wearing the right eye polarization filter 22a and the left eye polarization filter 22b with different polarization directions on the right eye and the left eye of the subject, respectively. When the first polarization direction and the third polarization direction are the same or differ slightly (for example, less than 45 degrees), even if the right eye polarization filter 22a and the left eye polarization filter 22b with different polarization directions are used, it is possible that the image of another chart other than the target chart is projected to each subject's eye. Preferably, when the first polarization direction and the third polarization direction differ by 90 degrees, and the polarization directions of the right eye polarization filter 22a and the left eye polarization filter 22b also differ by 90 degrees, it is possible to most completely prevent the image of another chart other than the target chart from being projected, which is preferred.

[0031] When the image display device is an organic light-emitting device (OLED) or other image display device that does not have polarization, a polarization filter with a predetermined polarization angle can be attached to the image display device to form a polarization table projector. When the image display device does not include a polarization film in the internal structure and independently projects a polarized image in a liquid crystal display device (LCD), it can be used directly without attaching a separate polarization film. For example, since the small (5.7 / 5 inch) LCD used in smartphones and the like generally has a polarization angle of 45 degrees, it can be used directly without attaching a separate polarization film. In addition, when the polarization degree of the LCD module itself is not high, a polarization film of the corresponding angle can also be further attached for use.

[0032] In a preferred embodiment of the present invention, Figure 4 As shown, the first image display device 30a and the second image display device 30b are arranged facing each other and at an angle of 90 degrees, and the beam splitter 50 is arranged between the first image display device 30a and the second image display device 30b at an angle of 45 degrees. In addition, it is preferred that the optical sensor 60 is located on the path of the table image that is reflected by the beam splitter 50 and does not proceed to the subject's eye 5 and / or the table image that passes through the beam splitter 50 and does not proceed to the subject's eye 5. In this case, the first image display device 30a and the second image display device 30b emit a first table image 40a and a second table image 40b polarized at 45 degrees. The first table image 40a polarized at 45 degrees is directly projected to the subject through the beam splitter 50, and the second table image 40b polarized at 45 degrees is reflected by the beam splitter 50, thereby projecting the second table image 40b polarized at 135 degrees to the subject. It is preferable that the first surface image 40 a with polarization of 45 degrees and the second surface image 40 b with polarization of 135 degrees are transmitted to the subject in parallel with each other.

[0033] Although the present invention is described above with reference to the accompanying drawings and exemplary embodiments, the present invention is not limited to the contents shown in the drawings and the above-mentioned embodiments, and should be interpreted as covering all variations, equivalent structures and functions of the embodiments within the scope of the claims. In the claims, although the figure numerals are marked to facilitate understanding, the scope of the claims is not limited to the figure numerals and the contents shown in the drawings.

Claims

1. A table projector for visual acuity examination, characterized in that: include: One or more image display devices (30a, 30b) that generate vision test chart images (40a, 40b); a beam splitter (50) which, when generating the surface image (40a) in the direction of sight of the eye (5) to be examined, allows a portion of the surface image (40a) to pass through so as to illuminate the eye (5) to be examined, and reflects the remaining portion so as to block illumination of the eye (5) to be examined, and, when generating the surface image (40b) on the side of the direction of sight of the eye (5) to be examined, allows a portion of the surface image (40b) to reflect so as to illuminate the eye (5) to be examined, and allows the remaining portion to pass through so as to block illumination of the eye (5) to be examined; and A light sensor (60) measures the brightness of a table image (40a) reflected by the beam splitter (50) to calculate the brightness of a table image (40a) for vision testing emitted to an eye under test (5) through the beam splitter (50), or measures the brightness of a table image (40b) passed through the beam splitter (50) to calculate the brightness of a table image (40b) for vision testing reflected by the beam splitter (50) to emit to an eye under test (5).

2. The eye examination chart projector according to claim 1, characterized in that: The optical sensor (60) is located on a path of a surface image (40a) that is reflected by the beam splitter (50) but does not proceed to the subject's eye (5) or a surface image (40b) that passes through the beam splitter (50) but does not proceed to the subject's eye (5).

3. The eye examination chart projector according to claim 1, characterized in that: The beam splitter (50) is a half mirror that reflects a portion of incident light and allows another portion to pass.

4. The eye examination chart projector according to claim 1, characterized in that: The brightness of the vision test chart images (40a, 40b) emitted by the image display devices (30a, 30b) is adjusted according to the brightness of the vision test chart images (40a, 40b) detected by the optical sensor (60).

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